It is well known to provide a device for chemical analysis of a sample in which the device is provided with a number of compressible chambers containing solid or liquid chemical or biochemical formulations such that, by compressing a number of the chambers in a particular sequence, the required chemical test can be carried out on a sample which has been inserted into the testing device. Such a device is typically hand-held and therefore the sample can be inserted into the testing device almost immediately after it has been obtained and the test performed. In this way, it is possible for a user of such a device to obtain the results of the test very quickly. Further advantages of using a microfluidic system are that small sample volumes can be used, compatible with, for example, finger prick blood samples, small reagent volumes are required, thereby leading to reduced cost for each test and small amounts of waste materials, which can be retained on or within the device. Furthermore, the devices provide a high surface area to volume ratio, thereby giving fast binding and reaction speeds. As the devices are typically compact, they are readily compatible for use, for example, in ambulances, in emergency rooms, at home or in GP surgeries.
For example, EP 0381501 discloses a cuvette for use in PCR technology and which confines all of the reagents within the device, thereby preventing errant DNA escaping the cuvette and contaminating further testing apparatus. The device includes multiple chambers which contain the reagents and, in use, the chambers are compressed by an external pressure means. The chambers are in fluid communication with a central mixing area through thin pathways such that compression of the chambers forces the required sample and reagents into the mixing chamber in a predetermined sequence. The device is comprised of two layers, both of which are at least partially shaped to provide the flexible chambers and the fluid pathways.
U.S. Pat. No. 3,476,515 discloses a flexible testing device having a plurality of compartments for storing reagents and for carrying out the necessary reaction. The chambers are pressure activated, in use, to expel the reagent from that chamber into a mixing chamber. The results of the reaction carried out in the mixing chamber can then be analysed by a further machine which measures the spectral characteristics with an appropriate photometer, such as a spectrophotometer or by measuring the thermal, chemical, physical, electrical or electrochemical properties of the end product of the reaction.
A further example of this type of device has been provided by i-STAT Corporation and is known by names such as i-Stat CG8+ cartridge. This device provides a series of sensors over which, in turn, a calibration fluid and a sample are passed. The calibration fluid is directed to the sensor from one region with one specific action and then the sample is directed to the same sensor from a different location with a second action.
It is important, however, that wet and dry reagents are kept apart prior to analysis so that they do not become contaminated, thereby adversely affecting the actual analysis which is to be carried out.
It is an aim of the present invention to provide a disposable device for chemical analysis of a sample which is simple to manufacture and easy to operate and which ensures that all the reagents are kept apart before analysis.